Honda Gxv120 Rebuild-mystery part?

Boats.net came through on my Honda parts a little more than a week after ordering them. Not bad, and they really did seem to have the lowest prices. So today I picked up some assembly lube, a piston ring compressor, a 3/8ths torque wrench and went to work. First came putting the piston back into the cylinder-not too bad a job, just be VERY careful to align the rings with the mark facing "up." My mark was a "N" instead of a "T" but I think I got it right.
 
Next was the crankshaft (lube it up, drop it in the bearing) and the the connecting rod cap. When you tighten the connecting rod bolts, make sure you are using a torque wrench! The space you have to work in is really tight so I actually went and picked up a new one for the occasion. The sears store only had a 3/8ths drive, but a 1/4" probably would have worked even better if I had thought ahead and ordered it online.

After the crankshaft and piston are back together, move on to the camshaft. Make sure the dots line up, the lifters are back in their slots, and drop it in. I didn't mark the lifters as I took them out...but they appear to have no wear and be identical.

So far so good...until I found a mystery part! Shit, I hate it when that happens! Here is a picture of the little sucker:

This little guy shows up in the parts sheet on boats.net as a "pipe, oil defense" in the cylinder head parts diagram.  Unfortunately, it shows up nowhere in the manual, and in the parts diagram it is off in the corner by itself...no clue to where in the cylinder head it lives. Hmmm...so dear readers, anybody know where things thing goes?

Tools used to reassemble the gxv120 piston, crank and camshaft:

1/4-Inch Torque Wrench
Piston Ring Compressor
Engine Assembly Lube